#!/usr/bin/env python3

import sys


def trailhead_score(tm, x, y):
    height = tm[y][x]
    end_positions = set([])
    if height == 9: return set([(x,y)])
    directions = [(0,1), (1,0), (0,-1), (-1,0)]
    for d in directions:
        nx, ny = x+d[0], y+d[1]
        if nx < 0 or ny < 0: continue
        try:
            if tm[ny][nx] - height == 1:
                end_positions = end_positions.union(trailhead_score(tm, nx, ny))
        except IndexError: continue
    return end_positions


def trailhead_ranking(tm, x, y):
    height = tm[y][x]
    score = 0
    if height == 9: return 1
    directions = [(0,1), (1,0), (0,-1), (-1,0)]
    for d in directions:
        nx, ny = x+d[0], y+d[1]
        if nx < 0 or ny < 0: continue
        try:
            if tm[ny][nx] - height == 1:
                score += trailhead_ranking(tm, nx, ny)
        except IndexError: continue
    return score


if __name__ == '__main__':
    tm = [[int(l) for l in line.strip('\n')] for line in open(sys.argv[1])]
    res1, res2 = 0, 0
    for j, y in enumerate(tm):
        for i, x in enumerate(y):
            if x == 0:
                res1 += len(trailhead_score(tm, i, j))
                res2 += trailhead_ranking(tm, i, j)

    # challenge 1
    print(f"challenge 1:\n{res1}\n")

    # challenge 2
    print(f"challenge 2:\n{res2}")